Step 1

Heat oven to 350°F (325°F for dark or nonstick pan). Grease bottom of 9-inch square pan with shortening or cooking spray. In small bowl, mix cream cheese and sugar with spoon until smooth. Add flour, egg white and vanilla; mix until well blended. Set aside.

Step 2

Make brownie batter as directed on box, adding reserved egg yolk. Reserve 1/2 cup brownie batter; set aside. Spread remaining batter in pan. Spoon filling by tablespoonful dollops evenly onto batter, making 3 rows by 3 rows. Spoon about 1 tablespoon of the reserved brownie batter in center of each filling dollop. Draw knife through mixture in four straight lines horizontally, then vertically for swirled design. Sprinkle with chocolate chips.

Step 3

Bake 28 to 32 minutes or until toothpick inserted 2 inches from side of pan comes out almost clean. Cool 30 minutes on cooling rack. Refrigerate at least 1 hour until chilled. Cut into 4 rows by 4 rows. Store covered in refrigerator.